1. Field of the Invention
Various embodiments of the invention relate to the area of optical communications photonic integrated circuits (PICs). In particular, the embodiments described herein generally relate to integrated widely tunable optical transmitters capable of generating optical signals in various modulation formats at different optical wavelengths for optical communications applications.
2. Description of the Related Art
As demand for higher capacity in optical networks continues to grow, ways to increase optical network capacity with reduced capital investment are of interest. One cost efficient solution that allows for reduction in capital investment is chip-scale integration of optical components, such as, for example, optical transmitters and receivers, which can allow for mass production of these devices. These tunable devices can be made to support a number of modulation formats, such as traditional amplitude modulation, On-Off Keying, as well as more complex modulation formats, Quadrature Amplitude Modulation (QAM), Phase Shift Keying (PSK), and Quadrature Phase Shift Keying (QPSK). Modulation formats such as Quadrature Phase Shift Keying and Quadrature Amplitude Modulation can allow for a number of data symbols to be sent utilizing the same line rate as a lower bit-rate On-Off keyed system. The complex modulation formats can be spectrally efficient and can improve the efficiency of fiber Wavelength Division Multiplexing (WDM). Spectrally efficient modulation formats can also allow for maximum utilization of the existing optical network infrastructure with increased data throughput capacity.